The invention relates to a
machining method for an engine connecting rod. The
machining method for the engine connecting rod includes the following steps that (a) the two end surfaces of the connecting rod are subjected to rough
grinding, a small-head hole is drilled and enlarged, a large-head hole and the small-head hole are subjected to rough boring, the small-head hole is subjected to semi-finished boring, a bolt boss is milled, a bolt hole is drilled or tapped, and deburring is carried out; (b) linear
cutting is carried out on the position, corresponding to a
cracking plane, of the inner edge of the large-head hole to form a V-shaped
cracking groove, and the V-shaped
cracking groove is symmetrical relative to the cracking plane to form an initial cracking source; (c) the connecting rod is heated to 150-250 DEG C, a
hydraulic cylinder drives a bidirectional wedge block to move downwards and be pressed into a semicircular movable sleeve, the semicircular movable sleeve is pushed to act on the inner wall of the large-head hole, the large-head hole is cracked instantly, a connecting rod cover and a connecting rod body are separated, and cold water is sprayed; and (d) the cracked connecting rod is subjected to fine
machining, and a cracked connecting rod finished product is formed. The connecting rod is heated and sprayed with the cold water after the connecting rod cover and the connecting rod body are separated, the strength of the engine connecting rod can be improved, and the levelness of the cracking plane of the connecting rod cover and the connecting rod body can be improved as well.